Winter Weather Outlook
The National Weather Service's Climate Prediction Center anticipates that there will be a strong El Niño this upcoming winter and their latest precipitation outlook for December through March indicates that Marin is likely to receive higher than average amounts of precipitation. Additionally, due in part to warmer than average ocean waters, tides could be significantly higher than predicted.
Regardless of predictions, the Marin County Flood Control & Water Conservation District (District) prepares for every year as though it is an “El Niño year.” Although two major flooding years in Marin's history occurred during years with El Niño episodes (1997/98 and 1982/83), it is not unusual to experience major flooding in the absence of El Niño, such as in 2005/06. Flooding can even occur during a drought year such as last year, when the County suffered some of its worst flooding damage since 2006.
It is for these reasons that the District follows a consistent system of facility and creek maintenance each year which mitigates the risk of flooding. We conduct regular inspections of the creeks, floodwalls, and levees within our jurisdiction, and frequently test our pumps, motors, and generators. Creeks, drainage ditches, pipes, trash racks, and pump wet wells are cleared of vegetation, sediment, and trash in the fall and throughout the winter as needed. A flood control zone-specific update regarding maintenance, storm preparedness and response in your local area is provided below.
Pump Station Maintenance
All scheduled annual pump maintenance will be completed by the end of October. This includes both major maintenance for select pumps and electric motors, as well as preventative maintenance for all pumps/motors. (Individual pumps and motors are scheduled for major maintenance on a six year interval.)
Due for planned maintenance this year were pump #1 at Crest Marin, pump #2 at Shoreline, and pump #1 at Ryan Creek. The amount budgeted for completing this work was $80,000 and all work was completed under budget at a cost of $54,910.
Pumps not due for preventative maintenance are tested and routine maintenance and repair is performed as necessary. Each year before the rainy season, the pump stations’ electrical components are tested and the engines are maintained. The generators at Cardinal Road, Ryan Creek, and Shoreline pump stations were just load tested with no issue. The pump station wet wells are also cleaned as needed to optimize pump operation.
The Conservation Corps North Bay performed annual vegetation maintenance along the Coyote Creek Levee. The District also entered into its annual agreement with the City of Mill Valley under which the City oversees maintenance and then normally receives up to $35,000 in reimbursements from the District. The City is considering increasing maintenance and preparing for more frequent post-storm cleanup this year; so we may increase their reimbursement up to $50,000 in an effort to accommodate their request.
Vegetation maintenance is being permitted through a Routine Maintenance Agreement with the CA Department of Fish and Wildlife (DFW) which streamlines the permit acquisition process.
The need for sediment removal was assessed earlier this year at multiple locations where sediment removal has been performed in the past. Individual permits are being sought from the San Francisco Regional Water Quality Control Board for sediment removal along Nyhan Creek at Enterprise Concourse and along Sutton Manor Creek downstream of Ashford Ave. A programmatic permit has been secured for this work from California Fish & Wildlife. Work is scheduled to take place prior to October 15.
Levee/Floodwall Maintenance & Rodent Control
The levee is inspected biennially (i.e., every other summer) by the Army Corps of Engineers and District staff. Minor patch repairs of the concrete channel in Coyote Creek are conducted by county staff and/or contractors as needed. Each year County staff inspects, cleans, greases, and repairs as necessary the tide gates on the pipes that penetrate the channel wall. This year the District completed an inspection of the inside of these pipes and will use the inspection results to prioritize pipe rehabilitation in the future.
Rodent control efforts on the earthen levees are ongoing, and are conducted in accordance with the County’s Integrated Pest Management policy. Traps will be set early this fall and, following successful rodent removal, holes will be filled with bentonite grout to restore the levee fill material. Residents who notice rodent activity can contact the District to request information on how to fight burrowing rodents in their yards and/or report problems in nearby levees to have traps set near the levees.
Precipitation and Stream Gage Maintenance
The District owns several precipitation and stream gauges throughout the county which help inform us of water levels in creeks and heavy rainfall in real-time. Zone 3 has gauge sites in Tam Valley at Coyote Creek, upper Coyote Creek, and Arroyo Corte Madera del Presidio. Visit https://marin.onerain.com/home.php for more information on the gauges. As needed preventative maintenance on the gauges is performed twice annually - September/October and February/March.
The Conservation Corps North Bay inspects and clears facilities as needed before, during, and after storms. They are also available for sandbagging and/or tarping levees and creek banks if requested. The District keeps sand and bags at the Crest Marin Pump Station for authorized emergency use only. Additionally, County crews make rounds to all District pump stations to make sure they are in working order, and receive alarms from the pump stations to warn of emergency situations.
The District has a fleet of portable pumps which are maintained and tested prior to the winter season and some are pre-deployed in key locations. The nearest pumps that are not pre-deployed are stored at Shoreline Pump Station (in Zone 3) and Pamela Court Pump Station (in Zone 4).
The District is evaluating and has received a bid for temporary removable flood barriers which could be deployed quickly and in lieu of sandbags at flood threatened locations. The barriers are made of high strength plastic and achieve their stability by filling them with water.